Lifting jack



s. SELDEN.

LIFTING JACK.

.APPLICATION man APR. s. 1921,.

1922. 2sHEETs-sHEET|.

Patented Apr. 25

/I/ll L INVENTOR. 5 SA/705.4551052 S.. SELDEN. I

LIFTING JACK.

APPLICATION FILED APR. 6| 1921.

1,413,793, f Patented Apr.2 5,1922.

2 SHEETS-SHEET 2.

I N VEN TOR. 54m/5L 55mm! SAMUEL sELDEN, or DENVER, Gonone-DQl LIrTiNGJAcK.

To cZZ whom it may cofrzc'ern.'V

Be it known that I, SAMUEL SELDEN, a citizen of the United States, residing at-Denver, in the county of Denver and State of Colorado, have invented certain new and useful Improvements in Liftingdaclrs, of which the following is a specification.

This invention relates to lever jacks of the double action type inl which two pawls are carried on an operating lever at opposite sides of the fulcrum thereof to alternately liftthe load by up and downward movement of the same.

The main object oft'he present invention is 'to provide in a jack ofthe above described character, a reversing device ofl simple construction which in anadjusted position operates to separate the pawls alternately,7 from the teeth of the raclrbar Awith which they normally engage, for the purpose of lowering the load by the reciprocating motion of the operating lever'.

Another object of the inventionis to provide in connection withthe reversing mechanism, springs which act upon the paw'ls to maintain them in .operative relation to the rack bar during the lifting action, and' still other objects residev in the construction and arrangement of part-s shownin the accompanyingdrawingsin the several views of which corresponding parts aire similarly designated and in which- Figure 1 is a side elevation of a lifting i jack to which the improved reversing mechanism is applied; Y

Figure 2, a section taken on the line 2-2, Figure 1; Figure 3, a fragmentary sectional elevation ofthe operating parts ofthe jack in the position occupy during the lifting action; Figure 4, a view similar to Figure 3 showing the reversing device in its operative relation to vthe lifting pawls which are shown in" their position Vat the end of thedown stroke of the' lever;

Figure 5, a view similar to Figure il showing the parts in their position at the end of the tip-stroke ofthe lever; j Figure 6, a fragmentary elevation ofthe jack with part of the side plate of its housing broken away to show the eccentric movement of the reversing mechanism; Y

Figure 7, a similar LView after the eccentric adjusting element of theV mechanism is removed;

Specification of Letters Patent. `Patgnted `ing plate 7.

which hold the paw'ls vin engagement with the rac-lr bar during 'theliftin'g action.

Referring tov thedrawin'gs'by numerical characters of reference the improved lifting Jack comprises a standard 5 of ordinary form and construction in which a'raclr bar 6 'has a vertical sliding movement. Aplate 7 4detachably fastened at a side of the stand@ ard covers fa housing inwhich the'parts of the lifting and reversing mechanismsf'are 'cooperatively assembled.

The operating lever 'of usual is composed of a metal socket Sand a wooden handle 9 removably insertedt'h'erein, is fulcrumed on theI standard by means of a transverse pin l0 and it has -twoshoulders l@ and 13 which limitY its @reciprocating movement byv engagement Vwith a correspond- Y ing lpart of the standard and one of the lift ing pawls hereinafterto be described. f

the jack which"l The operating lever has at opposite sides of its fulcrum open seats adapted to sup'- port the tri'innioned ends of two lifting pawls 14 and 15 which arefpositioned with relation to the rack bar to constantly engage Jthe teeth thereof by gravity- In the operationiof the j ack tolift a load supportedV on'the .rack`-bar, the downward stroke lof 'the lever causes the'l'ower andf'shorter pawl V14 to raise the raclcbar while the other,

longer pawl 15 rides idly across the' teeth thereof and when the movement ofthe le ver isreversed the upper pa'wl is forced to act upon the rack bar while the other pawl mactively returns to its original position.

The reversing mechanism lof the present invention yby whichthe pawls'are caused to alternately sustain the-load on the rack bar during its downward movement, comprises a carrier16 which 'by means ofl al laterally projecting pin '17 is slidablysupportedin a horizontal slot' 18 of a plate 19^whi"ch is 'fastened insidethe housing of the standardin spaced relation to the before-mentioned clos- An eccentric Q0 rotatably supported on the if pin is heldin place by a head at the outer end thereof and it has forwardly projecting thumb wings inside ran opening of the cover plate to facilitate its rotation for the purpose of sliding the carrier in the slot of the plate 19.

The eccentric is movably tted inside a ring 2l formed at the end of a radial extending arm 2la which at its outer extremity is pivotal-ly supported on the plate l9 by means of a screw pin 28.

Attached at one of their ends respectively at the upper and lower sides of the carrier are two forwardly projecting leaf springs 22 and 28 which in the operative position of the reversing device are respectively engaged by studs 24 and 25'which project laterally from the two lifting pawls.V

The upper spring curves upwardly and extends below the respective stud of the upper pawl, and the lower spring which extends partially above the stud of the pawl 14 has va reversely bent end portion 23EL extending slantingly beneath the same.

When the jack is used to lift the load the carrier is in its extreme forward position in which the springs are out of the paths of travel of the respective studs of the pawls when by up and downward movement of the lever the latter are operated to alternately act upon the rack bar as hereinbefore described.

It will thus be seen that in the operation of the jack as a lifting medium, the springs of the reversing device are idle and that gravity is the only force relied upon to maintainthe pawls in engagement with the teeth of the rack bar. However, should varying conditions require the use of springs to constantly maintain the operative relation of the pawls to the rack bar, they may be readily applied to the sliding carrier of the reversing mechanism as shown in Figure l() of the drawings in which two additional springs 26 and 27 attached at the upper and lower ends of the carrier by the same fastening` means which secure the beforementioned springs 22 and 28, are formed to respectively bear upon the studs on the pawls when the reversing device is in its inoperative position.

When it is desired to lower the load upon the rack-bar, the pawls are employed to alternately sustain the weight thereof during their downward motion in the reciproeating movement of the operating lever, through the medium of the springs 22 and 23 on the sliding carrier after the latter has been adjusted by rotation of the eccentric to its operative position illustrated in Figures 4 and 5.

When with the parts in this position the operatingl lever is reciprocated the springs are alternately engaged by the respective studs on the pawls and so deflected that at imanes the termination of each stroke of the lever one of the pawls is forced out of engagement with the teeth of the rack bar. To be more specific, when the upper pawl is lowered by downward movement of the lever it sustains the downwardly moving load on the rack bar by engagement with the teeth thereof while the lower pawl which previously was separated from the rack bar by the action of the spring 23 as will hereinafter be described, is gradually returned to its original position by the movement of its stud along the slanting terminal portion of the spring.

lThe stud on the upper pawl has meanwhile engaged the upper spring on the carrier and gradually deects it to the position shown in broken lines in Figure l until the lever reaches the end of its downward stroke when under the law of restitution it causes the pawl to disengage the teeth of the rack bar and move it to the position shown in full lines in the same view.

When the lever is subsequently moved upwardly the downwardly moving lower pawl sustains the load on the rack bar while the upper pawl gradually approaches the rack bar by the movement of its stud along the up-V wardly curving portion of the upper spring until at the end of the stroke it has again moved in engagement with the teeth thereof. The stud on the lower pawl is in the meantime brought in engagement with the terminal part of the lower spring which there-V by is deflected as shown in broken lines in [Figure 5 and which when the lever reaches the end of its upward movement, causes the pawl to disengage the teeth of the rack bar and moves it to the position shown in full lines in Figure 5.

In the modified construction shown in Figures 8 and 9 of the drawings, the carrier is adjusted vertically instead of horizontally to bring its springs in operative relation to the studs on the lifting pawls. Thesprings are of slightly different form from those of the first-described construction, the slot in the plate 19 in which the carrier is guided and the ring around the eccentric is fastened A at right angles to its former position.

The operation of the modified reversing device is the same as that hereinbefore described with relation to the original constructionv1 the position of the springs on the carrier in the operative position thereof having` been shown in broken lines in Figure 8.

Having thus described my invention what claim and desire to secure by Letters-Patent is:

l. ln a lifting aclnthe combination of a rack-bar, lifting pawls engaging the teeth thereof, a lever in operative relation t0 the pawls, and a reversing device comprising an adjustable carrier7 and springs on the carrier normally disengaged from the paWls and adapted to engage the pavvls in an adjusted position of the 'carrier to alternately force them out of engagement With the teeth of the rack bar in the operation of the jack by movement of the lever.

2. ln a lifting jack, the combination of a rack-bar, lifting paWls engaging the teeth thereof, a. lever in operative relation to the pawls, and a reversing device comprising an adjustable carrier, spring-members on the carrier normally disengaged from the pawls and adaplted to engage the paivls in an adjusted position of the carrier to alternately force them out of engagement with the teeth of the rack bar in the operation of the jack by movement of the lever, and a spring member on the carrier which in its normal position engages the paivls to hold them in engagement with the rack bar. v

23. In a lifting jack, the combination of a rack-bar, lifting paWls engaging the teeth thereof and having laterally projecting studs, a lever in operative relation to the pawls, and a reversing device comprising an adjustable carrier, and springs on the carH rier normally disengaged Vfrom the. studs and adapted. to bear upon the studs When` Vlthe carrier is in its adjusted position, to

alternately lift the pavvls out of engagement with the teeth of the rack bar in the' operation of the jack by movement ofthe lever.

4. ln a lifting jack, the combination of a rack bar, lifting paWls engaging the teeth thereof and having laterally projecting studs, a lever in operative relation to the paivls, and afreversing device comprising an adjustablev carrier, spring-members on the carrier normally disengaged from the studs and adapted to engage With the same in an adjusted position of 'the carrier to alternately force them out of engagement with the teeth of the rack bar in the opera tion of the jack by movement of the lever, and a spring member on the carrier which in.

engage with the studs on the pawls, in an adjusted position of the same.,

6. In a lifting jack, 4the combination of a rack bar, lifting paWls engaging the teeth thereof, and having laterally projecting studs, a reciprocating lever in operative relation to the pa'wls, and a reversing device comprising an adjustable carrier, and springs on the carrier normally disengaged from the studs and adapted to engage With the same in the adjusted position of` the carrier. to alternately disengage the paWls from the teeth on the rack bar at the ends of the reciprocating movement` of the lever.

7. In a lifting ack, the combination of a rack bar, lifting vpavvls `engaging the teethr thereof, an operating lever, and a reversing device 'comp-rising a sliding cai'rier and slanting springs on the carrier adapted to engage with projections on the pavvls in an adjusted lposition of the same.

8., In a lifting jack, the combinationvof a rack-bar, lifting paivls engaging the teeth thereof, a lever in operative relation toV the pawls,andareversing device comprising a sliding carrier, and springs on the carrier normally disengaged from the pavvls and adapted' to engage the pawls in an adjusted position of the carrier to alternately force them vout of engagement Withthe teeth of the rack-bar in the operation ofthe jack by movement of the lever.

In' testimony whereof l have affixed my signature. i

SAMUEL sELDEN. 

